Multifunctional cationic photoinitiators, their preparation and use

ABSTRACT

Compounds of formula (I): 
     
       
         
         
             
             
         
       
     
     [where: R 1  is a direct bond, oxygen, a group &gt;CH 2 , sulphur, a group &gt;C═O, a group —(CH 2 ) 2 — or a group —N—R a , where R a  is hydrogen or alkyl; R 3 , R 4 , R 5  and R 6  are hydrogen or substituents α; R 8 , R 9 , R 10  and R 11  are hydrogen, hydroxy or alkyl; or R 9  and R 11  are joined to form a fused ring system with the benzene rings to which they are attached; R 7  is a direct bond, oxygen or a —CH 2 — group; p is 0 or 1; substituents α are: alkyl, alkoxy, alkenyl, halogen, nitrile, hydroxyl, aryl, aralkyl, aryloxy, aralkyloxy, arylalkenyl, cycloalkyl, carboxy, carboxyalkoxy, alkoxycarbonyl, aryloxycarbonyl, alkylcarbonyloxy, alkanesulphonyl, arenesulphonyl, alkanoyl or arylcarbonyl; n is 1 to 12; R 12  is hydrogen, methyl or ethyl; A is a group —[O(CHR 13 CHR 14 ) a ] y —, —[O(CH 2 ) b CO] y —, or —[O(CH 2 ) b CO] (y-1) —[O(CHR 13 CHR 14 ) a ]—, where: one of R 13  and R 14  is hydrogen and the other is hydrogen, methyl or ethyl; a is 1 to 2; b is 4 to 5; Q is a residue of a polyhydroxy compound having from 2 to 6 hydroxy groups; x is a number greater than 1 but no greater than the number of available hydroxyl groups in Q; y is a number from 1 to 10; and X −  is an anion]; and esters thereof are useful as cationic photoinitiators, especially for use in surface coating applications, such as printing inks and varnishes, and which are intended to be cured by polymerisation initiated by radiation.

The present invention relates to a series of novel sulphonium saltswhich are useful as multifunctional cationic photoinitiators, especiallyfor use in surface coating applications, such as printing inks andvarnishes, and which are intended to be cured by polymerisationinitiated by radiation.

Photocurable compositions are cured by exposure to radiation, usuallyultraviolet radiation, and include for example, lacquers which may beapplied to wood, metal or similar substrates by suitable techniques suchas roll coating or curtain coating. They may also be formulated as inks,for example to be applied by techniques such as letterpress, offsetlithography, rotogravure printing, silk screen printing, inkjet orflexographic printing. Printing, depending on the particular printingtechnique, is applicable to a wide range of substrates which includepaper, board, glass, plastics materials or metals. Other applicationareas will include adhesives, powder coatings, circuit boards andmicroelectronic products, stereolithography, composites, optical fibresand liquid crystals.

Initiation of polymerisation in a monomer, oligomer or prepolymer may beeffected in a number of ways. One such way is by irradiation, forexample with ultraviolet radiation, in which case it is normallynecessary mat the polymerisable composition should contain an initiator,commonly referred to as a “photoinitiator”, or alternatively by anelectron beam. There are two main types of curing chemistry which can beused in this process; free radical and cationic. Although cationiccuring has many advantages, its disadvantages, particularly with regardto the photoinitiators used, leads it to be used only in a minority ofapplications. Most frequently used cationic initiators are eitherorganic iodonium or sulphonium salts.

Briefly, the mechanism by which a sulphonium cationic initiator actswhen irradiated is that it forms an excited state which then breaks downto release a radical cation. This radical cation reacts with thesolvent, or another hydrogen atom donor, generating a protonic acid. Theactive species is the protonic acid. However, amongst the breakdownproducts of sulphonium salts are aromatic sulphides, such as diphenylsulphide, which are malodorous and can be a health hazard, and loweraromatic hydrocarbons, such as benzene, which are potentiallycarcinogenic. Many of the commonly used iodonium salts break down togive volatile species such as benzene, toluene or isobutyl benzene. Thisplaces sever restrictions upon the applications for which such cationicphotoinitiators can be used. For example, they cannot be used inprinting inks on packaging intended for food or is likely to come intocontact with food, and, in some cases, cannot be used at all where thepackaging is to be handled by the consumer. Indeed, as the industrybecomes ever more conscious of health matters, it is increasinglydifficult to use such compounds at all and there is, therefore, anurgent need to find compounds suitable for use as photoinitiators andwhose breakdown products are generally regarded as safe.

However, this, although important, is not the only constraint upon thechoice of compound to be used as a cationic photoinitiator. Even withoutconsideration of the health issues, the cleavage products of the knowncationic photoinitiators are malodorous, and it is highly desirable thatunpleasant odours should be minimised. This leads to a desire that thecleavage products should be relatively non-volatile and non-odorous. Thecationic photoinitiators must, of course, also be sufficiently stable,both as isolated compounds and when in the uncured coating formulation.They must also be soluble in or miscible with other components of theuncured coating formulation. Finally, they should be able to absorbradiation over a suitable and sufficiently wide range of wavelengths,ideally without the use of a sensitiser.

What is more, the nature of the cationic photoinitiator can have a majorimpact on the properties of the cured coating. The cationicphotoinitiator should produce a coating which is fully cured, hard andresistant to common solvents and abuse.

Finally, there are a number of practical problems associated with themanufacture of the compounds used as cationic photoinitiators, includingthe necessity that they should be relatively easy and inexpensive tomanufacture.

Thus, it would be desirable to provide a cationic photoinitiator whichdoes not generate malodorous or toxic by-products upon radiation cure,particularly diphenyl sulphide and benzene, and so which may be used forprinting packaging which may come into contact with food. Moreover, itis a common desideratum in this field that the photoinitiator shouldpossess the following properties: good solubility, good cureperformance, good adhesion to substrates and reasonable cost.

Not surprisingly, complying with all of these, often conflicting,requirements is not easy, and we are not aware of any completelysatisfactory commercial solution available until now.

However, we have now discovered a series of new derivatives ofthioxanthone and similar fused ring compounds, whose breakdown productsinclude examples mat are widely used as free radical photoinitiators andwhose safety is not in question. Moreover, many of these compounds havethe advantages of good solubility in the coating composition combinedwith excellent cure.

Thus, the present invention provides photoinitiator compounds of formula(I):

where:

R¹ represents a direct bond, an oxygen atom, a group >CH₂, a sulphuratom, a group >C═O, a group —(CH₂)₂ or a group of formula —N—R^(a),where R^(a) represents a hydrogen atom or a C₁-C₁₂ alkyl group;R³, R⁴, R⁵ and R⁶ are independently selected from hydrogen atoms andsubstituents α, defined below;R⁸, R⁹, R¹⁰ and R¹¹ are independently selected from hydrogen atoms,hydroxy groups, C₁-C₄ alkyl groups, and phenyl groups which areunsubstituted or substituted by at least one substituent selected fromthe group consisting of C₁-C₄ alkyl groups and C₁-C₄ alkoxy groups;or R⁹ and R¹¹ are joined to form a fused ring system with the benzenerings to which they are attached;R⁷ represents a direct bond, an oxygen atom or —CH₂— group;p is 0 or 1;said substituents α are: a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, aC₂-C₂₀ alkenyl group, a halogen atom, a nitrile group, a hydroxyl group,a C₆-C₁₀ aryl group, a C₇-C₁₃ aralkyl group, a C₆-C₁₀ aryloxy group, aC₇-C₁₃ aralkyloxy group, a C₉-C₁₂ arylalkenyl group, a C₃-C₈ cycloalkylgroup, a carboxy group, a C₂-C₇ carboxyalkoxy group, a C₂-C₇alkoxycarbonyl group, a C₇-C₁₃ aryloxycarbonyl group, a C₂-C₇alkylcarbonyloxy group, a C₁-C₆ alkanesulphonyl group, a C₆-C₁₀arenesulphonyl group, a C₁-C₆ alkanoyl group or a C₇-C₁₁ arylcarbonylgroup;n is a number from 1 to 12;R¹² represents a hydrogen atom, a methyl group or an ethyl group, and,when n is greater than 1, the groups or atoms represented by R¹² may bethe same as or different from each other;A represents a group of formula —[O(CHR¹³CHR¹⁴)_(a)]_(y)—,—[O(CH₂)_(b)CO]_(y)—, or —[O(CH₂)_(b)CO]_((y-1))—[O(CHR¹³CHR¹⁴)_(a)]—,where:one of R¹³ and R¹⁴ represents a hydrogen atom and the other represents ahydrogen atom, a methyl group or an ethyl group;a is a number from 1 to 2;b is a number from 4 to 5;Q is a residue of a polyhydroxy compound having from 2 to 6 hydroxygroups;x is a number greater than 1 but no greater than the number of availablehydroxyl groups in Q;y is a number from 1 to 10; andX⁻ represents an anion;and esters thereof.

These compounds are useful as photoinitiators for use in energy, e.g.UV, curable coating compositions, including varnishes, lacquers andprinting inks, most especially printing inks.

The compounds of the present invention may, as described above, be usedas cationic photoinitiators for radiation-curable coating compositions.Thus, the present invention also provides an energy-curable compositioncomprising: (a) a polymerisable monomer, prepolymer or oligomer,especially a material which undergoes acid-catalysed ring openingpolymerisation, e.g. an epoxide (oxirane) or oxetane, or anethylenically unsaturated material, such as vinyl or propenyl ethers and(b) a cationic photoinitiator which is a compound of formula (I), asdefined above, or an ester thereof.

The invention still further provides a process for preparing a curedpolymeric composition by exposing a composition of the present inventionto curing energy, preferably ultraviolet radiation.

Preferably, when x is a number greater than 1 but no greater than 2, yis a number from 1 to 10; or when x is a number greater than 2, y is anumber from 3 to 10.

Where R¹ represents a group of formula —N—R^(a), R^(a) represents ahydrogen atom or an alkyl group having from 1 to 12 carbon atoms, morepreferably from 1 to 6 carbon atoms, and most preferably from 1 to 4carbon atoms, for example any of the alkyl groups having this number ofcarbon atoms and described below in relation to R³ etc., preferably ahydrogen atom or a methyl or ethyl group.

However, we most prefer those compounds in which R¹ represents agroup >C═O, a sulphur atom or a direct bond, and especially those inwhich R¹ represents a group >C═O.

More preferred are those compounds of formula (I) in which the residueof formula (IV):

is a residue of substituted or unsubstituted thianthrene,dibenzothiophene, thioxanthone, thioxanthene, phenoxathiin orphenothiazine, especially those in which said residue is a substitutedor unsubstituted thioxanthone.

We also particularly prefer compounds in which p is 0.

Where R³, R⁴, R⁵ or represents an alkyl group having from 1 to 20,preferably from 1 to 10, more preferably from 1 to 6 and most preferablyfrom 1 to 3, carbon atoms, this may be a straight or branched chaingroup, and examples of such groups include the methyl, ethyl, propyl,isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl,2-methylbutyl, 1-ethylpropyl, 4-methylpentyl, 3-methylpentyl,2-methylpentyl, 1-methylpentyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl,1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl,2,3-dimethylbutyl, 2-ethylbutyl, hexyl, isohexyl, heptyl, octyl, nonyl,decyl, dodecyl, tridecyl, pentadecyl, octadecyl, nonadecyl and icosylgroups, but preferably the methyl, ethyl, propyl, isopropyl and t-butylgroups, and most preferably the ethyl or isopropyl group.

Where R³, R⁴, R⁵ or R⁶ represents an alkoxy group having from 1 to 20,preferably from 1 to 10, more preferably from 1 to 6 and most preferablyfrom 1 to 3, carbon atoms, this may be a straight or branched chaingroup, and examples of such groups include the methoxy, ethoxy, propoxy,isopropoxy, butoxy, isobutoxy, t-butoxy, pentyloxy, isopentyloxy,neopentyloxy, 2-methylbutoxy, 1-ethylpropoxy, 4-methylpentyloxy,3-methylpentyloxy, 2-methylpentyloxy, 1-methylpentyloxy,3,3-dimethylbutoxy, 2,2-dimethylbutoxy, 1,1-dimethylbutoxy,1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,3-dimethylbutoxy,2-ethylbutoxy, hexyloxy, isohexyloxy, heptyloxy, 2-ethylhexyloxy,octyloxy, nonyloxy, decyloxy, dodecyloxy, tridecyloxy, pentadecyloxy,octadecyloxy, nonadecyloxy and icosyloxy groups, but preferably themethoxy, ethoxy, t-butoxy and 2-ethylhexyloxy groups, and mostpreferably the 2-ethylhexyloxy group.

Where R³, R⁴, R⁵ or R⁶ represents an alkenyl group having from 2 to 20,preferably from 2 to 10, more preferably from 2 to 6 and most preferablyfrom 2 to 4, carbon atoms, this may be a straight or branched chaingroup, and examples of such groups include the vinyl, 1-propenyl, allyl,isopropenyl, methallyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl,nonenyl, decenyl, dodecenyl, tridecenyl, pentadecenyl, octadecenyl,nonadecenyl and icosenyl groups, but preferably the allyl, methallyl andbutenyl groups, and most preferably the allyl group.

Where R³, R⁴, R⁵ or R⁶ represents a halogen atom, this may be, forexample, a fluorine, chlorine, bromine or iodine atom, preferably achlorine atom.

Where R³, R⁴, R⁵ or R⁶ represents an aryl group, this has from 6 to 10carbon atoms in one or more aromatic carbocyclic rings (which, if thereare more than one, may be fused together). Such a group may besubstituted or unsubstituted, and, if substituted, the substituent(s) ispreferably an alkyl or alkoxy group (as defined above), or analkoxycarbonyl group (as defined below). Preferred aryl groups are thephenyl and naphthyl (1- or 2-) groups, the phenyl group being mostpreferred.

Where R³, R⁴, R⁵ or R⁶ represents an aryloxy group, this may be any ofthe aryl groups above bonded to an oxygen atom, and examples include thephenoxy and naphthyloxy groups.

Where R³, R⁴, R⁵ or R⁶ represents an aralkyl group, this is an alkylgroup having from 1 to 4 carbon atoms which is substituted by one or twoaryl groups as defined and exemplified above. Examples of such aralkylgroups include the benzyl, α-phenylethyl, β-phenylethyl, 3-phenylpropyl,4-phenylbutyl, diphenylmethyl, 1-naphthylmethyl and 2-naphthylmethylgroups, of which the benzyl group is preferred.

Where R³, R⁴, R⁵ or R⁶ represents an aralkyloxy group, this may be anyof the aralkyl groups above bonded to an oxygen atom, and examplesinclude the benzyloxy, α-phenylethoxy, β-phenylethoxy, 3-phenylpropoxy,4-phenylbutoxy, diphenylmethoxy, 1-naphthylmethoxy and 2-naphthylmethoxygroups, of which the benzyloxy group is preferred.

Where R³, R⁴, R⁵ or R⁶ represents an arylalkenyl group having from 8 to12 carbon atoms, the aryl and alkenyl parts of this group may be asdefined and exemplified above for the respective component parts.Specific examples of such groups are the styryl and cinnamyl groups.

Where R³, R⁴, R⁵ or R⁶ represents a cycloalkyl group having from 3 to 8carbon atoms, this may be, for example, the cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl group.

Where R³, R⁴, R⁵ or R⁶ represents a carboxyalkoxy group, this may be anyof fee alkoxy groups having from 1 to 6 carbon atoms described abovewhich is substituted by a carboxy group. Preferred examples include thecarboxymethoxy, 2-carboxyethoxy and 4-carboxybutoxy groups, of which thecarboxymethoxy group is preferred.

Where R³, R⁴, R⁵ or R⁶ represents an alkoxycarbonyl group, this has from1 to 6-carbon atoms in the alkoxy part, and thus a total of from 2 to 7carbon atoms. It may be a straight or branched chain group, and examplesof such groups include the methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl,t-butoxycarbonyl, pentyloxycarbonyl, isopentyloxycarbonyl,neopentyloxycarbonyl, 2-methylbutoxycarbonyl, 1-ethylpropoxycarbonyl,4-methylpentyloxycarbonyl, 3-methylpentyloxycarbonyl,2-methylpentyloxycarbonyl, 1-methylpentyloxycarbonyl,3,3-dimethylbutoxycarbonyl, 2,2-dimethylbutoxycarbonyl,1,1-dimethylbutoxycarbonyl, 1,2-dimethylbutoxycarbonyl,1,3-dimethylbutoxycarbonyl, 2,3-dimethylbutoxycarbonyl,2-ethylbutoxycarbonyl, hexyloxycarbonyl and isohexyloxycarbonyl groups,but preferably the methoxycarbonyl, ethoxycarbonyl and t-butoxycarbonylgroups, and most preferably the methoxycarbonyl or ethoxycarbonyl group.

Where R³, R⁴, R⁵ or R⁶ represents an aryloxycarbonyl group having from 7to 13 carbon atoms, the aryl part of this may be any of the aryl groupsdefined and exemplified above. Specific examples of such groups includethe phenoxycarbonyl and naphthyloxycarbonyl groups.

Where R³, R⁴, R⁵ or R⁶ represents an alkylcarbonyloxy group having from2 to 7 carbon atoms, this may be any of the alkoxycarbonyl groupsdefined and exemplified above bonded to an oxygen atom.

Where R³, R⁴, R⁵ or R⁶ represents an alkanesulphonyl group, this hasfrom 1 to 6 carbon atoms and is a straight or branched chain group.Examples of such groups include the methanesulphonyl, ethanesulphonyl,propanesulphonyl, isopropanesulphonyl, butanesulphonyl,isobutanesulphonyl, t-butanesulphonyl, pentanesulphonyl andhexanesulphonyl groups, of which the methanesulphonyl group ispreferred.

Where R³, R⁴, R⁵ or R⁶ represents an arenesulphonyl group, the aryl partmay be as defined and exemplified above, and examples include thebenzenesulphonyl and n-toluenesulphonyl groups.

Where R³, R⁴, R⁵ or R⁶ represents an alkanoyl group having from 1 to 6carbon atoms, and preferably from 1 to 4 carbon atoms, this may be astraight or branched-chain group, and examples include the formyl,acetyl, propionyl, butyryl, isobutyryl, pivaloyl, valeryl, isovaleryl,and hexanoyl groups, of which the acetyl group is most preferred.

Where R³, R⁴, R⁵ or R⁶ represents an arylcarbonyl group, the aryl parthas from 6 to 10, more preferably 6 or 10, and most preferably 6, ringcarbon atoms and is a carbocyclic group, which is unsubstituted or hasfrom 1 to 5, preferably from 1 to 3 substituents, as defined andexemplified above. The preferred groups are the benzoyl and naphthoylgroups.

We particularly prefer those compounds of formula (I) in which R³, R⁴R⁵and R⁶ are individually the same or different and each represents ahydrogen atom, an alkyl group having from 1 to 10 carbon atoms, analkoxy group having from 1 to 10 carbon atoms, a halogen atom, or acycloalkyl group having from 3 to 8 carbon atoms More preferredcompounds are those in which either two or three of R³, R⁴, R⁵ and R⁶represent hydrogen atoms, and still more preferably those in which oneor two of R³, R⁴, R⁵ and R⁶ represents an ethyl or isopropyl group, orthose in which three or four of R³, R⁴, R⁵ and R⁶ represent hydrogenatoms. The most preferred compounds are those in which one or two of R³,R⁴, R⁵ and R⁶ represent ethyl groups or in which one of R³, R⁴, R⁵ andR⁶ represents an isopropyl group and the others represent hydrogenatoms.

Where R⁸, R⁹, R¹⁰ or R¹¹ represents an alkyl group, this may be astraight or branched chain alkyl group having from 1 to 4 carbon atoms,and examples include the methyl, ethyl, propyl, isopropyl, butyl,isobutyl and t-butyl groups, of which the methyl group is preferred.

Where R⁸, R⁹, R¹⁰ or R¹¹ represents a phenyl group, this may beunsubstituted or it may be substituted with one or more substituentsselected from the group consisting of C₁-C₄ alkyl and C₁-C₄ alkoxygroups. The alkyl and alkoxy substituents may be any of the alkyl groupsexemplified above in relation to R⁸, R⁹, R¹⁰ or R¹¹ above or any of thealkoxy groups having from 1 to 4 carbon atoms selected from the alkoxygroups exemplified in relation to R³, R⁴, R⁵ or R⁶ above. Examples ofsuch groups include the phenyl group, the o-, m- or p-tolyl group, theo-, m- or p-methoxyphenyl group, the o-, m- or p-ethoxyphenyl group, theo-, m- or p-propoxyphenyl group, the o-, m- or p-butoxyphenyl group, theo-, m- or p- t-butoxyphenyl group, the 2,4,6-trimethylphenyl group andthe 2,4,6-trimethoxyphenyl group. Of these, the unsubstituted phenylgroup is preferred.

In one preferred embodiment of the present invention, p is 0, R¹⁰ is aphenyl group, and R¹¹ is a hydrogen atom. In this embodiment, weparticularly prefer that the group of formula —O—(CHR¹²)_(n)— should beattached to the benzene ring on which is a substituent in the paraposition to R¹⁰, and the sulphur atom of the three membered fused ringsystem should be in the para position to R¹⁰.

We prefer those compounds of formula (I) in which two, three or four ofR⁸, R⁹, R¹⁰ and R¹¹ represent hydrogen atoms, and especially those inwhich all of R⁸, R⁹, R¹⁰ and R¹¹ represent hydrogen atoms.

When R⁹ and R¹¹ together with the benzene rings to which they areattached, form a fused ring system, this may be, for example, abiphenylene, fluorene or phenanthrene system, preferably fluorene.

R⁷ may be a direct bond (so that the two groups joined by R⁷ togetherform biphenylyl group), an oxygen atom (so that the two groups joined byR⁷ together form a phenoxyphenyl group), or a methylene group (so thatthe two groups joined by R⁷ together form a benzylphenyl group).

n is a number from 1 to 12, more preferably from 1 to 6, and mostpreferably 1.

We particularly prefer compounds in which R¹² represents a hydrogenatom, and especially compounds in which R¹² represents a hydrogen atomand n is 1. Alternatively, we prefer compounds in which n is a numberfrom 2 to 6 and one group R¹² represents a hydrogen atom, or a methyl orethyl group and the other or others of R¹² represent hydrogen atoms.

In the compounds of the present invention, we prefer that A shouldrepresent a group of formula —[O(CHR¹³CHR¹⁴)_(a)]_(y)— where a is aninteger from 1 to 2, and y is as defined above, preferably a number from3 to 10, more preferably a group of formula —[OCH₂CH₂]_(y)—,—[OCH₂CH₂CH₂CH₂]_(y)— or [OCH(CH₃)CH₂]_(y)—, where y is as definedabove, preferably a number from 3 to 10, or a group of formula—[O(CH₂)_(b)CO]_(y)— or —[O(CH₂)_(b)CO]_(y)— or—[O(CH₂)_(b)CO]_((y-1))—[O(CHR¹³CHR¹⁴)_(a)]—, where b is a number from 4to 5 and y is as defined above, preferably a number from 3 to 10. Stillmore preferably, y is a number from 3 to 6.

In general, in the compounds of the present invention, y is preferably anumber from 3 to 10, more preferably from 3 to 6. We also prefercompounds of formula (I) in which x is 2 and y is a number from 1 to 10.

It is a feature of the present invention that the compounds are of agenerally polymeric nature. The polymeric nature may be provided byeither the group represented by Q or the group represented by A or byboth.

The polymeric polyhydroxy residue of formula Q-(A-)^(x), which forms thecore of the compounds of the present invention has a major influence onthe behaviour of the compounds. In accordance with the presentinvention, it is important mat it should have a polymeric nature, sincethe resulting compounds tend to be liquid or of low melting point, thusaiding dispersion in the coating composition. Compounds having a similarstructure but not polymeric tend to be solid and/or insoluble in thesecoating compositions. However, we prefer that the core residue, offormula Q-(A-)_(x), should not have too high a molecular weight, andprefer mat the residue of formula Q-(A-)_(x) should have a molecularweight no greater than 2000, preferably no greater than 1200, still morepreferably no greater than 1000, and most preferably no greater than800.

We particularly prefer that Q should be a residue of ethylene glycol,propylene glycol, butylene glycol, glycerol, trimethylolpropane,di-trimethylolpropane, pentaerythritol or di-pentaerythritol.

It will be appreciated that, when the compounds of the present inventionare analysed, the numbers a, b and y in the above formulae need not beintegral, and, indeed, it is unlikely mat they will be integral, sincethe compounds of the present invention may be mixtures of severalcompounds in which the numbers a, b and y differ. In accordance with thepresent invention, provided that the average value of each of thesenumbers is as defined above, this will be satisfactory. Of course, foreach individual molecule of the compounds of the present invention, a, band y will be integral, and it might be possible to separate out suchindividual compounds, but, in practice, mixtures of these compounds areused.

X⁻ represents an anion. In general, there is no particular limitation onthe nature of the anion to be used. However, where the compounds of thepresent invention are to be used as photoinitiators, the anion should benon-nucleophilic, or essentially non-nucleophilic, as is well known inthe art. It should also be relatively bulky. If the compounds are not tobe used as photoinitiators, the anion need not meet these requirements.For example, in some cases, it may be desirable not to store thecompound in the form of the salt which is ultimately to be used. In thatcase, it may be preferable to form another salt, and men convert thecompound to the desired salt at or close to the point of use. In such acase, it is not necessary that the anion should be non-nucleophilic.

Examples of non-nucleophilic anions are well known to those skilled inthe art, and include anions of formula MZ_(s) ⁻ where M represents aphosphorus, boron, antimony, arsenic, chlorine or carbon atom, Zrepresents a halogen atom except where M represents a halogen atom, anoxygen atom or a sulphite group, and s is an integer dependent upon thevalence of M and Z. Preferred examples of such groups include the PF₆ ⁻,SbF₆ ⁻, AsF₆ ⁻, BF₄ ⁻, B(C₆F₅)₄ ⁻, R^(b)B(Ph)₃ ⁻ (where R^(b) representsan alkyl group having from 1 to 6 carbon atoms and Ph represents aphenyl group), R^(c)SO₃ ⁻ (where R^(c) represents an alkyl or haloalkylgroup having from 1 to 6 carbon atoms or an aryl group), ClO₄ ⁻ andArSO₃ ⁻ (where Ar represents an aryl group) groups, of which the PF₆ ⁻,SbF₆ ⁻, AsF₆ ⁻, CF₃SO₃ ⁻ and BF₄ ⁻ groups are preferred and the PF₆ ⁻group is most preferred.

Where the compounds of the present invention contain a carboxy group,i.e. where R³, R⁴, R⁵ or R⁶ represents a carboxy or carboxyalkoxy group,the resulting compounds may form esters, and these esters also form apart of the present invention. There is no particular limitation on thenature of the ester, other than those constraints well known to thoseskilled in the art, and preferred examples of esters include the alkylesters, particularly those having from 1 to 12 carbon atoms, such asthose containing the C₁-C₁₂ alkyl groups, and those derived from apolyalkylene glycol ether ester (especially the C₁-C₄ alkyl ethers),such as esters containing groups of formula:

—[OR¹⁵]_(t)OR¹⁶

where R¹⁵ represents an alkylene group having torn 1 to 8 carbon atoms,R¹⁶ represents an alkyl group having from 1 to 4 carbon atoms, and t isa number from 2 to 20, preferably from 5 to 10. More preferred aregroups of formula:

—[OCH₂CHR¹⁷]_(t)OR¹⁶

where R¹⁶ and t are as defined above and R¹⁷ represents an alkyl grouphaving from 1 to 4 carbon atoms.

Any combination of the preferred substituent groups and atoms listedabove in respect of R¹, R³, R⁴, R⁵, R⁶, R⁸, R⁹, R¹⁰, R¹¹, R¹², is alsoenvisaged by the present invention.

Particularly preferred compounds of the present invention having anespecially good combination of good cure and good solubility in coatingcompositions are those compounds of formula (I) in which:

R³, R⁴, R⁵ and R⁶ are individually the same or different and eachrepresents a hydrogen atom or an alkyl group having from 1 to 4 carbonatoms;R⁷ represents a direct bond;R⁸, R⁹, R¹⁰ and R¹¹ represent hydrogen atoms, and especially suchcompounds where p is 0; andA represents a group of formula —[OCH₂CH₂CH₂CH₂]_(y)—; andQ represents a residue of butylene glycol.

A further preferred class of compounds of the present invention arethose compounds of formula (I) in which:

R³, R⁴, R⁵ and R⁶ are individually the same or different and eachrepresents a hydrogen atom or an alkyl group having from 1 to 4 carbonatoms;R⁷ represents a direct bond;R⁸, R⁹, and R¹¹ represent hydrogen atoms;R¹⁰ represents a phenyl group;p is 0;A represents a group of formula —[OCH₂CH₂CH₂CH₂]_(y)—; andQ represents a residue of butylene glycol.

The compounds of the present invention may be prepared by reactions wellknown for the preparation of compounds of this type, the exact reactionroute chosen depending upon the nature of the compound which it isdesired to prepare.

The compounds of the present invention may be prepared by reacting asulphoxide corresponding to ring system (IV), i.e. a compound of formula(II), with the compound corresponding to the remainder of the moleculeof the desired compound, i.e. a compound of formula (III), in thepresence of an acid, as shown in the following scheme:

In the above formulae, R¹, R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², A,Q, n, p and x are as defined above, and Y⁻ represents an anion, forexample a hydroxy group, which will normally be derived from thereaction. Where any one or more of R⁸, R⁹, R¹⁰, or R¹¹ represents ahydroxy group, this is preferably protected, since it otherwise mayreact with the acid used in the reaction. The nature of the protectinggroup used is not critical to the invention, and any protecting groupknown in the art for use in compounds of this type may equally be usedhere, for example an ester group. Examples of suitable protecting groupsare described in “Protective Groups in Organic Synthesis” by T. W.Greene and P. G. M. Wuts, Second Edition, 1991, published by John Wiley& Sons, Inc.

The reaction is normally and preferably effected in a solvent, thenature of which is not critical, provided that it has no adverse effecton the reagents or on the reaction and provided that it can dissolve thereagents, at least to some extent. A suitable solvent is acetic acid.

The reaction is also preferably effected in the presence of aceticanhydride and more preferably in the presence of a strong acid.Preferred is a combination of concentrated sulphuric acid and aceticanhydride.

A suitable reaction temperature is preferably below 15° C.

The sulphoxide of formula (II) and the polymeric compound of formula(III) may be prepared by well known methods.

Using the reaction scheme above, it is possible to obtain yields inexcess of 90% in each reaction step, which assists the economics of theprocess.

In general, the anion Y⁻ will not be the anion X⁻ which it is desired toincorporate in fee final product. If so, then the desired anion may beintroduced by an anion exchange reaction, as is well known in the fieldof synthetic chemistry.

Where a protected hydroxy group represented by R⁸, R⁹, R¹⁰, or R¹¹ ispresent, the protecting group may, if desired, be removed by methodswell known to those skilled in the art, as described in “ProtectiveGroups in Organic Synthesis” above.

The compounds of the invention may then be separated from the reactionmixture by well known techniques and, if desired, further purified.

The composition of the present invention may be formulated as a printingink, varnish, adhesive or any other coating composition which isintended to be cured by irradiation, whether by ultraviolet or electronbeam. Such compositions will normally contain at least a polymerisablemonomer, prepolymer or oligomer, and the cationic photoinitiator of thepresent invention, but may also include other components well known tothose skilled in the art, for example, reactive diluents and, in thecase of printing inks, a pigment.

A wide variety of monomers and prepolymers may be subjected to cationicphotoinitiation using the compounds of the present invention asphotoinitiators, and the nature of the monomers and prepolymers is notcritical to the present invention. Such monomers and prepolymerstypically contain cationically polymerisable groups, and generalexamples of such compounds include the epoxides, oxetanes, other cyclicethers, vinyl compounds (such as vinyl and propenyl ethers, styrene andits derivatives and unsaturated polyesters), unsaturated hydrocarbons,lactones and, in the case of hybrid systems, acrylates andmethacrylates.

Typical epoxides which may be used include the cycloaliphatic epoxides(such as those sold under the designations UVR6110 by Union Carbide orUVACURE 1500 by UCB), which are well known to those skilled in the art.

Other epoxy-functional oligomers/monomers which may be used include theglycidyl others of polyols [bisphenol A, alkyl diols or poly(alkyleneoxides), which be di, tri-, tetra- or hexa-functional]. Also, epoxidesderived by the epoxidation of unsaturated materials may also be used(e.g. epoxidised soybean oil, epoxidised polybutadiene or epoxidisedalkenes). Naturally occurring epoxides may also be used, including thecrop oil collected from Vernonia galamensis.

As well as epoxides, other reactive monomers/oligomers which may be usedinclude the vinyl ethers of polyols [such as triethylene glycol divinylether, 1,4-cyclohexane dimethanol divinyl ether and the vinyl ethers ofpoly(alkylene oxides)]. Examples of vinyl ether functional prepolymersinclude the urethane-based products supplied by Allied Signal.Similarly, monomers/oligomers containing propenyl ether groups may beused in place of the corresponding compounds referred to abovecontaining vinyl ether groups.

Similarly, compounds bearing oxetane groups may be used in place of thecorresponding compounds referred to above containing epoxide groups. Atypical oxetane is that derived from trimethylolpropane(3-ethyl-3-hydroxymethyloxetane).

Other reactive species can include styrene derivatives and cyclic esters(such as lactones and their derivatives).

It is also common to include polyols in ultraviolet cationic curableformulations, which promote the cross-linking by a chain-transferprocess. Examples of polyols include the ethoxylated/propoxylatedderivatives of, for example, trimethylolpropane, pentaerythritol,di-trimethylolpropane, di-pentaerythritol and sorbitan esters, as wellas more conventional polyethylene oxide)s and poly(propylene oxide)s.Other polyols well known to those skilled in the art are thepolycaprolactone diols, triols and tetraols, such as those supplied byUnion Carbide.

Additives which may be used in conjunction with the principal componentsof the coating formulations of the present invention includestabilisers, plasticisers, pigments, waxes, slip aids, levelling aids,adhesion promoters, surfactants and fillers. Also, compounds which actas sensitisers for the photoinitiator, such as thioxanthone (andderivatives), benzophenone (and derivatives), hydroxyalkylphenones,anthracene (and derivatives), perylene, xanthone, pyrene andanthraquinone, may be included.

The compounds of the present invention may be included asphotoinitiators in coating formulations such are well known in the art,and the precise composition of such formulations will vary dependingupon the other components and the intended use, as is well known.However, a typical formulation for an ink coatable by flexography mightbe:

Pigment 8-20% Photoinitiator 2-6% Monomer/prepolymer/oligomer 30-90%Polyol 0-30% Additives 0-10%

In order to enhance the solubility of the compounds of the presentinvention in the curable composition, they may first be dissolved in asuitable solvent, for example propylene carbonate.

The invention is further illustrated by the following non-limitingExamples.

EXAMPLE 1 Preparation of 2-isopropylthioxanthone sulphoxide

10.0 g (0.03937 moles) of 2-isopropylthioxanthone were dissolved in 630ml of a mixture of acetonitrile and water (75% acetonitrile, 25% waterby volume). Gentle heating was required to dissolve the2-isopropylthioxanthone (35° C.). The temperature was then allowed toreturn to room temperature. 86.336 g of Ceric ammonium nitrate (0.15748moles) were added in one batch. The reaction was followed by TLC (thinlayer chromatography). The reaction mixture was stirred for 2.5 hours atroom temperature, 400 ml of water was then added and the mixture wasextracted with 1000 ml of diethyl ether. The ether layers were combinedand dried with magnesium sulphate, and the ether was removed on a rotaryevaporator to yield the product. At this stage the product stillcontained some inorganic residue. The product was therefore re-dissolvedin diethyl ether, washed with water and dried with magnesium sulphate.The ether was then removed on a rotary evaporator to yield the product.

Product yield 5.54 g (52.3%) of a yellow solid.

The product was analysed by HPLC, LC-MS and IR.

IR: 1074 cm⁻¹ and 1032 cm⁻¹ S═O due to sulphoxide.

MS: M/Z 271 (Mw of cation).

HPLC: one very strong peak due to product, with a change in retentiontime and a shift in the characteristic chromophore compared to thestarting material.

EXAMPLE 2 Preparation of Dibenzothiophene Sulphoxide

Dibenzothiophene (5.0 g, 0.027 mol) was added to acetic acid (20 ml),stirred and heated to 110° C.-120° C. until completely dissolved. Anexcess of peracetic acid (4.4 g, 0.0058 mol) was then added dropwise andthe reaction mixture was continuously stirred at this temperature forfour hours. The reaction was followed using TLC as an indication ofdibenzothiophene consumption. After cooling, the reaction mixture waspoured into water (40 ml), the resulting brown precipitate filtered off,washed with water and a small quantity of toluene (2-3 ml) before beingdried in a vacuum oven at 50° C.; for 4 hours.

Product yield 5.0 g (92%) of brown crystals.

The product was analysed by IR, HPLC and LC-MS.

IR: 1066 cm⁻¹ and 1024 cm⁻¹ S═O due to sulphoxide.

MS: M/Z 201 (Mw of cation).

HPLC: one very strong peak due to product, with a change in retentiontime and a shift in the characteristic chromophore compared to thestarting material.

EXAMPLE 3

Phenoxyacetic acid (33.44 g, 0.22 mols), polytetrahydrofuran (250molecular weight, 25 g, 0.1 mols), 0.5 g p-toluenesulphonic acid, 0.1 gbutylated hydroxytoluene and 200 ml toluene were azeotropically refluxedfor 2.25 hours. The solution was washed with 2×75 ml 10% aqueouspotassium carbonate solution and 100 ml deionised water beforeazeotroping to dryness, filtering and removing all solvent on a rotaryevaporator.

Yield=52.2 g slightly yellow low viscosity liquid

The product was analysed by IR.

IR: 1757-1735 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 4

5 g of the product from Example 3 (0.00996 moles), 5.38 g of the productfrom Example 1 (0.0199 moles), acetic acid (18.6 ml), acetic anhydride(18.6 ml) and dichloromethane (4.7 ml) were mixed in a round-bottomedflask. The temperature of the mixture was reduced to <15° C. using awater/ice bath. Concentrated sulphuric acid (6.9 ml) was then addeddrop-wise, making sure the temperature did not exceed 15° C. Afteraddition was complete, the mixture was stirred for two hours, allowingthe temperature to increase to room temperature. 100 ml of water wasthen added and the solution was extracted with 2×100 ml dichloromethane.The dichloromethane was men removed on a rotary evaporator to yield23.75 g of intermediate product. This was dissolved in a minimum ofacetic acid and poured into a KPF₆ solution (5.6 g in 180 ml water).This appeared to yield a viscous liquid which was extracted withdichloromethane and washed with 3×100 ml water before drying overmagnesium sulphate and removing all solvent on a rotary evaporator.

Product yield 11.86 g (91.7%) of a brown liquid.

Product analysed by IR.

IR: 845 cm⁻¹ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 5

0.94 g of the product from Example 3 (0.00187 moles), 0.75 g of theproduct from Example 2 (0.00375 moles), acetic acid (3.5 ml), aceticanhydride (3.5 ml) and dichloromethane (0.9 ml) were mixed in around-bottomed flask. The temperature of the mixture was reduced to <15°C. using a water/ice bath. Concentrated sulphuric acid (1.3 ml) was thenadded drop-wise, making sure the temperature did not exceed 15° C. Afteraddition was complete, the mixture was stirred for two hours, allowingthe temperature to increase to room temperature. 60 ml of water was thenadded and the solution was extracted with 2×50 ml dichloromethane. Thedichloromethane was men removed on a rotary evaporator to yield 2.87 gof intermediate product. This was dissolved in a minimum of acetic acidand poured into a KPF₆ solution (2.0 g in 60 ml water). This appeared toyield a viscous liquid which was extracted with dichloromethane andwashed with 3×100 ml water before drying over magnesium sulphate andremoving all solvent on a rotary evaporator.

Product yield 2.15 g (99.1%) of a brown liquid.

Product analysed by IR.

IR: 843 cm⁻¹ (strong) due to P—F salt of product.

The position of each dibenzothiophene system on the associated benzenering could not be determined exactly by analysis.

EXAMPLE 6

2-Phenoxypropionic acid (11.74 g, 0.07075 moles), polytetrahydrofuran(250 molecular weight, 7.69 g, 0.03076 moles), 0.16 g p-toluenesulphonicacid, 0.054 g butylated hydroxytoluene and 100 ml toluene wereazeotropically refluxed for 8.75 hours. The solution was washed with2×50 ml 10% aqueous potassium carbonate solution and 100 ml deionisedwater before drying over magnesium sulphate filtering and removing allsolvent on a rotary evaporator.

Yield= 17.52 g slightly yellow low viscosity liquid.

The product was analysed by IR.

IR: 1755-1734 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 7

2.0 g of the product from Example 6 (0.003663 moles), 1.98 g of theproduct from Example 1 (0.0199 moles), acetic acid (6.8 ml), aceticanhydride (6.8 ml) and dichloromethane (1.7 ml) were mixed in around-bottomed flask. The temperature of the mixture was reduced to <15°C. using a water/ice bath. Concentrated sulphuric acid (2.54 ml) wasthen added drop-wise, making sure the temperature did not exceed 15° C.After addition was complete, the mixture was stirred for two hours,allowing the temperature to increase to room temperature. 50 ml of waterwas then added and the solution was extracted with 2×50 mldichloromethane. The dichloromethane was then removed on a rotaryevaporator to yield 7.37 g of intermediate product. This was dissolvedin a minimum of acetic acid and poured into a KPF₆ solution 0.4 g in 50ml water). This appeared to yield a viscous liquid which was extractedwith dichloromethane and washed with 3×100 ml water before drying overmagnesium sulphate and removing all solvent on a rotary evaporator.

Product yield 4.29 g (87.3%) of a brown liquid.

Product analysed by IR.

IR: 845 cm⁻¹ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 8

11-Phenoxyundecanoic acid (4.61 g, 0.01656 moles), polytetrahydrofuran(250 molecular weight, 1.80 g, 0.0072 moles), 0.04 g p-toluenesulphonicacid, 0.013 g butylated hydroxytoluene and 25 ml toluene wereazeotropically refluxed for 9 hours. The solution was washed with 2×50ml 10% aqueous potassium carbonate solution and 100 ml deionised waterbefore drying over magnesium sulphate, filtering and removing allsolvent on a rotary evaporator.

Yield=5.72 g slightly yellow solid.

The product was analysed by IR.

IR: 1736 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 9

2.0 g of the product from Example 8 (0.002595 moles), 1.4 g of theproduct from Example 1 (0.005185 moles), acetic acid (4.8 ml), aceticanhydride (4.8 ml) and dichloromethane (1.2 ml) were mixed in around-bottomed flask. The temperature of the mixture was reduced to <15°C. using a water/ice bath. Concentrated sulphuric acid (1.85 ml) wasthen added drop-wise, making sure the temperature did not exceed 15° C.After addition was complete, the mixture was stirred for two hours,allowing the temperature to increase to room temperature. 50 ml of waterwas then added and the solution was extracted with 2×50 mldichloromethane. The dichloromethane was then removed on a rotaryevaporator to yield 5.37 g of intermediate product. This was dissolvedin a minimum of acetic acid and poured into a KPF₆ solution (1.4 g in 50ml water). This appeared to yield a viscous liquid which was extractedwith dichloromethane and washed with 3×100 ml water before drying overmagnesium sulphate and removing all solvent on a rotary evaporator.

Product yield 2.98 g (89.95%) of a brown liquid.

Product analysed by IR.

IR: 845 cm⁻ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 10

Polytetrahydrofuran (250 molecular weight, 18.75 g, 0.075 mols),bromoacetic acid (22.9 g, 0.165 mols), 0.375 g p-toluenesulphonic acid,0.075 g butylated hydroxytoluene and 150 ml toluene were azeotropicallyrefluxed for 5 hours. The solution was washed with 2×100 ml 10% aqueouspotassium carbonate solution and 2×100 ml deionised water beforeazeotroping to dryness, filtering and removing all solvent on a rotaryevaporator.

Yield=36.3 g colourless low viscosity liquid.

The product was analysed by IR.

IR: 1736 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 11

5.0 g of 2-hydroxybiphenyl (0.0294 moles), 5.08 g potassium carbonatepowder (0.03676 moles) and 70 ml of methyl ethyl ketone were heated toreflux for 3 hours. The mixture was then cooled to room temperature and7.23 g of the product from Example 10 (0.0147 moles) were added. Themixture was then heated to reflux for a total 14 hours. The mixture wasthen cooled to room temperature. 50 ml of toluene was added and thesolution was washed with 2×100 ml 10% aqueous potassium carbonatesolution and 2×100 ml deionised water before drying over magnesiumsulphate. The solvent was then removed on a rotary evaporator.

Yield= 9.01 g of a slightly yellow liquid.

The product was analysed by IR.

IR: 1736 cm⁻ C═O due to ester, 1080 cm⁻¹ and 1190 cm⁻¹ due to alkyl-arylether.

EXAMPLE 12

4.0 g of the product from Example 11 (0.00597 moles), 3.224 g of theproduct from Example 1 (0.01194 moles), acetic acid (11.1 ml), aceticanhydride (11.1 ml) and dichloromethane (2.8 ml) were mixed in around-bottomed flask. The temperature of the mixture was reduced to <15°C. using a water/ice bath. Concentrated sulphuric acid (4.14 ml) wasthen added drop-wise, making sure the temperature did not exceed 15° C.After addition was complete, the mixture was stirred for two hours,allowing the temperature to increase to room temperature. 50 ml of waterwas then added and the solution was extracted with 2×50 mldichloromethane. The dichloromethane was then removed on a rotaryevaporator to yield 17.63 g of intermediate product. This was dissolvedin a minimum of acetic acid and poured into a KPF₆ solution (5.0 g in160 ml water). This appeared to yield a pasty dark green solid which wasfiltered, washed with water and men dried in a vacuum oven at 40° C.

Product yield 6.24 g (71.3%) of a dark green slightly sticky solid.

Product analysed by IR.

IR: 842 cm⁻¹ (strong) due to P—F salt of product.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 13

2-Phenoxypropionic acid (13.28 g, 0.07999 moles), ethoxylatedpentaerythritol (EO/OH 10/4) (10.0 g, 0.0173913 moles), 0.181 gp-toluenesulphonic acid, 0.061 butylated hydroxytoluene and 100 mltoluene were azeotropically refluxed for 13 hours. The solution waswashed with 2×50 ml 10% aqueous potassium carbonate solution and 100 mldeionised water before drying over magnesium sulphate, filtering andremoving all solvent on a rotary evaporator.

Yield= 19.56 g clear, slightly yellow low viscosity liquid.

The product was analysed by IR.

IR: 1751-1733 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 14

5.0 g of the product from Example 13 (0.0045289 moles), 3.47 g of theproduct from Example 1 (0.0128416 moles), acetic acid (16 ml), aceticanhydride (16 ml) and dichloromethane (4 ml) were mixed in around-bottomed flask. The temperature of the mixture was reduced to <15°C. using a water/ice bath. Concentrated sulphuric acid (5.94 ml) wasthen added drop-wise, making sure the temperature did not exceed 15° C.After addition was complete, the mixture was stirred for two hours,allowing the temperature to increase to room temperature. 50 ml of waterwas then added and the solution was extracted with 2×75 mldichloromethane. The dichloromethane was then removed on a rotaryevaporator to yield 20.78 g of intermediate product. This was dissolvedin a minimum of acetic acid and poured into a KPF₆ solution (6 g in 195ml water). A precipitate formed that was removed by filtration andwashed with water and men dried in the vacuum oven to constant weight.

Product yield 7.93 g (76.1%) of a brown solid.

Product analysed by IR.

IR: 842 cm⁻¹ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 15

2-Phenoxyacetic acid (12.16 g, 0.07999 moles), ethoxylatedpentaerythritol (EO/OH 10/4) (10.0 g, 0.017393 moles), 0.181 gp-toluenesulphonic acid, 0.061 g butylated hydroxytoluene and 100 mltoluene were azeotropically refluxed for 16½ hours. The solution waswashed with 2×50 ml 10% aqueous potassium carbonate solution and 100 mldeionised water before drying over magnesium sulphate filtering andremoving all solvent on a rotary evaporator.

Yield= 15.21 g clear, slightly yellow low viscosity liquid.

The product was analysed by IR.

IR: 1759 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 36

5.0 g of the product from Example 15 (0.0045004 moles), 4.86 g of theproduct from Example 1 (0.018 moles), acetic anhydride (14.72 g) weremixed in a round-bottomed flask. The temperature of the mixture wasreduced to <10° C. using a water/ice bath. Concentrated sulphuric acid<5.64 g) was then added drop-wise, making sure the temperature did notexceed 20° C. The contents of the flask were then added to a mixture of28.71 g methanol, 24.33 g water and 3.89 g potassiumhexafluorophosphate, 2.5 ml of methanol were also used to wash out thereaction vessel and added to the mixture. The mixture was then stirredat 35-40° C. for 30 minutes. The mixture was then cooled to <10° C. andstirred for a further 30 minutes. Stirring was then stopped and themixture was allowed to settle. The resulting residue was washed/decantedwith 2×50 g methanol/water mixture (55:45 ratio). This removed anysoluble impurities. The insoluble residue was then dried in the vacuumoven at 40° C. for 4 hours.

Product yield 9.0 g (73.98%) of a pasty brown solid.

Product analysed by IR.

IR; 841 cm⁻¹ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 17

2-Phenoxyacetic acid (25.46 g, 0.1675 moles), butoxylated trimethylolpropane (BuO/OH 7/4) (31.9 g, 0.05 moles), 0.5 g p-toluenesulphonicacid, 0.1 g butylated hydroxytoluene and 200 ml toluene wereazeotropically refluxed for 15 hours. The solution was washed with 2×100ml 10% aqueous potassium carbonate solution and 100 ml deionised waterbefore drying over magnesium sulphate, filtering and removing allsolvent on a rotary evaporator.

Yield=35.7 g clear, slightly straw coloured liquid.

The product was analysed by IR.

IR: 1760-1737 cm⁻¹ C═O (strong) due to ester. No OH peak present.

EXAMPLE 18

10.0 g of the product from Example 17 (0.0096153 moles), 7.79 g of theproduct from Example 1 (0.0288459 moles), acetic anhydride (23.6 g) weremixed in a round-bottomed flask. The temperature of the mixture wasreduced to <10° C. using a water/ice bath. Concentrated sulphuric acid(9.04 g) was then added drop-wise, making sure the temperature did notexceed 20° C. The contents of the flask were then added to a mixture of46 g methanol, 38.99 g water and 6.24 g potassium hexafluorophosphate.2.5 ml of methanol were also used to wash out the reaction vessel andadded to the mixture. The mixture was then stirred at 35-40° C. for 30minutes. The mixture was then cooled to <10° C. and stirred for afurther 30 minutes. Stirring was men stopped and the mixture was allowedto settle. The resulting residue was washed/decanted with3×methanol/water mixture (46 g/39 g). This removed any solubleimpurities. The insoluble residue was then dried in the vacuum oven at40° C. for 4 hours.

Product yield 6.53 g (30.40%) of a pasty brown solid.

Product analysed by IR, HPLC and GPC.

IR: 841 cm⁻¹ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 19

2-Phenoxyacetic acid (34.2 g, 0.225 moles), propoxylated pentaerythritol(PO/OH 17/8) (31.45 g, 0.05 moles), 0.5 g p-toluene sulphonic acid, 0.1g butylated hydroxytoluene and 200 ml toluene were azeotropicallyrefluxed for 15 hours. The solution was washed with 2×100 ml 10% aqueouspotassium carbonate solution and 100 ml deionised water before dryingover magnesium sulphate, filtering and removing all solvent on a rotaryevaporator.

Yield= 48.38 g (83.1%) clear, slightly straw coloured, low viscosityliquid.

The product was analysed by IR

IR: 1758-1738 cm⁻¹ C═O due to ester. No OH peak present

EXAMPLE 20

5.0 g of the product from Example 19 (0.0042918 moles), 4.635 g of theproduct from Example 1 (0.0171672 moles), acetic anhydride (14.05 g)were mixed in a round-bottomed flask. The temperature of the mixture wasreduced to <10° C. using a water/ice bath. Concentrated, sulphuric acid(5.38 g) was then added drop-wise, making sure the temperature did notexceed 20° C. The contents of the flask were then added to a mixture of27.38 g methanol, 23.2 g water and 3.71 g potassium hexafluorophosphate.2.5 ml of methanol were also used to wash out the reaction vessel andadded to the mixture. The mixture was then stirred at 35-40° C. for 30minutes. The mixture was men cooled to <10° C. and stirred for a further30 minutes. Stirring was then stopped and the mixture was allowed tosettle. The resulting residue was washed/decanted with 3×methanol/watermixture (27.38 g/23.2 g). This removed any soluble impurities. Theinsoluble residue was then dried in the vacuum oven at 40° C. for 4hours.

Product yield 5.47 g (46.23%) of a pasty yellow solid.

The product was analysed by IR.

IR: 841 cm⁻¹ (strong) due to P—F salt of product.

The position of each thioxanthone system on the associated benzene ringcould not be determined exactly by analysis.

EXAMPLE 21

Tripropylene glycol 14.42 g (0.075 moles)s bromoacetic acid 22.92 g(0.165 moles), p-toluenesulphonic acid 0.375 g, butylated hydroxytoluene0.075 g and toluene 50 ml were mixed in a two necked round-bottomedflask (flask 1) equipped with a temperature probe, condenser and Deanand Stark apparatus. The mixture was heated to reflux for 5 hours andthen cooled to room temperature and left overnight. In a second flask(flask 2) equipped with a stirrer, condenser and temperature probe2-hydroxybiphenyl 25.5 g (0.15 moles), potassium carbonate 25.91 g(0.1875 moles) and methyl ethyl ketone 100 ml were mixed and heated toreflux for 3 hours and men cooled to room temperature and leftovernight.

The contents of flask 1 were then added to flask 2. This mixture wasthen heated to reflux for a further 4 hours (86-87° C.). The mixture wasthen cooled to <=50° C. and filtered to remove the inorganics. Theinorganics were washed with a further 60 ml of methyl ethyl ketone whichwas then combined with the organic solution. The filter paper waspressed to maximise solvent and therefore product recovery. The organicswere then washed with 2×50 ml 10% potassium carbonate solution followedby 3×50 ml water (ensuring the washings were neutral pH). The organicswere men heated on a rotary evaporator to remove the organic solvent andany residual water (heating to 82° C. was required to drive off all ofthe solvent/water).

Product yield 41.67 g of a clear, slightly yellow liquid.

The product was analysed by IR.

IR: 1755-1737 cm⁻¹ C═O due to ester, 1076 cm⁻¹ and 1194 cm⁻¹ due toalkyl-aryl ether. No OH peak present.

EXAMPLE 22

10 g of the sample from Example 21 (0.0163 moles), 2-ITX sulphoxide, 8.8g (0.0326 moles) and acetic anhydride (20 g) were mixed in a 250 ml3-necked round bottomed flask equipped with a stirrer, thermometer anddropping funnel.

Acetic anhydride (30 g) was added to a beaker and cooled to 10° C.Concentrated sulphuric acid (7.8 g) was added slowly controlling thetemperature below 20° C. The resulting mixture was charged to thedropping runnel and added to the mixture in the flask. The addition tookapproximately 15 minutes and produced a black solution. This was stirredat room temperature for 20 minutes and then quenched slowly into amixture of potassium hexafluorophosphate (6.95 g), water (90 g) andacetonitrile (23 g), controlling the quenching temperature to 10-20° C.A solid started to form during the quenching process but, as additionprogressed, this turned into an oil. The product was isolated as an oilby decanting off excess water/acetonitrile. The product yield was notdetermined.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 23

PEG200 15.00 g (0.075 moles), bromoacetic acid 22.92 g (0.165 moles),p-toluenesulphonic acid 0.375 g, butylated hydroxytoluene 0.075 g andtoluene 50 ml were mixed in a two necked round-bottomed flask (flask 1)equipped with a temperature probe, condenser and Dean and Starkapparatus. The mixture was heated to reflux for 5 hours and then cooledto room temperature and left overnight. In a second flask (flask 2)equipped with a stirrer, condenser and temperature probe,2-hydroxybiphenyl 25.5 g (0.15 moles), potassium carbonate 25.93 g(0.1875 moles) and methyl ethyl ketone 100 ml were mixed and heated toreflux for 3 hours and then cooled to room temperature and leftovernight.

The contents of flask 1 were then added to flask 2. This mixture wasthen heated to reflux for a further 4 hours (86-87° C.). The mixture wasthen cooled to <= 50° C. and filtered to remove the inorganics. Theinorganics were washed with a further 60 ml of methyl ethyl ketone whichwas then combined with the organic solution. The filter paper waspressed to maximise solvent and therefore product recovery. The organicswere then washed with 2×50 ml 10% potassium carbonate solution followedby 3×50 ml water (ensuring the washings were neutral pH). The organicswere then heated on a rotary evaporator to remove the organic solventand any residual water (heating to 82° C. was required to drive off allof the solvent/water).

Product yield 19.54 g of a clear, slightly yellow liquid.

The product was analysed by BR.

IR: 1755-1737 cm⁻¹ C═O due to ester, 1076 cm⁻¹ and 1194 cm⁻¹ due toalkyl-aryl ether. No OH peak present.

EXAMPLE 24

10 g of the sample from Example 23 (0.0161 moles), 2-ITX sulphoxide, 8.7g (0.0322 moles) and acetic anhydride (20 g) were mixed in a 250 ml3-necked round bottomed flask equipped with a stirrer, thermometer anddropping funnel.

Acetic anhydride (30 g) was added to a beaker and cooled to 10° C.Concentrated sulphuric acid (7.8 g) was added slowly controlling thetemperature below 20° C. The resulting mixture was charged to thedropping funnel and added to the mixture in the flask. The addition tookapproximately 15 minutes and produced a black solution. This was stirredat room temperature for 20 minutes and then quenched slowly into amixture of potassium hexafluorophosphate (6.95 g), water (90 g) andacetonitrile (23 g), controlling the quenching temperature to 10-20° C.A solid started to form during the quenching process but, as additionprogressed, this turned into a gum. The product was isolated as a gum bydecanting off excess water/acetonitrile. The product yield was notdetermined.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 25

Ethoxylated pentaerythritol (3EO/4OH) 10.125 g (0.0375 moles),bromoacetic acid 22.92 g (0.165 moles), p-toluenesulphonic acid 0.375 g,butylated hydroxytoluene 0.075 g and toluene 50 ml were mixed in a twonecked round-bottomed flask (flask 1) equipped with a temperature probe,condenser and Dean and Stark apparatus. The mixture was heated to refluxfor 5 hours and then cooled to room temperature and left overnight. In asecond flask (flask 2) equipped with a stirrer, condenser andtemperature probe 2-hydroxybiphenyl 25.5 g (0.15 moles), potassiumcarbonate 25.91 g (0.1875 moles) and methyl ethyl ketone 100 ml weremixed and heated to reflux for 3 hours and then cooled to roomtemperature and left overnight.

The contents of flask 1 were then added to flask 2. This mixture wasthen heated to reflux for a further 4 hours (86-87° C.). The mixture wasthen cooled to <= 50° C. and filtered to remove the inorganics. Theinorganics were washed with a further 60 ml of methyl ethyl ketone whichwas men combined with the organic solution. The filter paper was pressedto maximise solvent and therefore product recovery. The organics werethen washed with 2×50 ml 10% potassium carbonate solution, followed by3×50 ml water (ensuring the washings were neutral pH). The organics werethen heated on a rotary evaporator to remove the organic solvent and anyresidual water (heating to 82° C. was required to drive off all of thesolvent/water).

Product yield 19.54 g of a clear, slightly yellow liquid.

The product was analysed by IR.

IR: 1757-1739 cm⁻¹ C═O due to ester, 1076 cm⁻¹ and 1194 cm⁻¹ due toalkyl-aryl ether. No OH peak present.

EXAMPLE 26

10 g of the sample from Example 25 (0.009 moles), 2-ITX sulphoxide, 9.7g (0.0359 moles) and acetic anhydride (10 g) were mixed in a 250 ml3-necked round bottomed flask equipped with a stirrer, thermometer anddropping funnel.

Acetic anhydride (19 g) was added to a beaker and cooled to 10° C.Concentrated sulphuric acid (8.6 g) was added slowly controlling thetemperature below 20° C. The resulting mixture was charged to thedropping funnel and added to the mixture in the flask. The addition tookapproximately 15 minutes and produced a black solution. The solution wasstirred at room temperature for 20 minutes and then quenched very slowly(over 2 hours) into a mixture of potassium hexafluorophosphate (7.6 g),water (60 g) and methanol (60 g), controlling the quenching temperatureto 0-5° C. A solid started to form during the quenching process andremained as a solid throughout. The solid was filtered off and washedwith deionised water (100 ml) and then dried to constant weight at 50°C.

Product yield of 22.3 g (91.8%) of a yellow solid.

The product was analysed by IR.

IR: 841 cm⁻¹ (strong) due to P—F salt of product.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 27

Ethoxylated pentaerythritol (10EO/4OH) 21.60 g (0.0375 moles),bromoacetic acid 22.92 g (0.165 moles), p-toluenesulphonic acid 0.375 g,butylated hydroxytoluene 0.075 g and toluene 50 ml were mixed in a twonecked round-bottomed flask (flask 1) equipped with a temperature probe,condenser and Dean and Stark apparatus. The mixture was heated to refluxfor 5 hours and then cooled to room temperature and left overnight. In asecond flask (flask 2) equipped with a stirrer, condenser andtemperature probe 2-hydroxybiphenyl 25.5 g (0.15 moles), potassiumcarbonate 25.91 g (0.1875 moles) and methyl ethyl ketone 100 ml weremixed and heated to reflux for 3 hours and then cooled to roomtemperature and left overnight.

The contents of flask 1 were then added to flask 2. This mixture wasthen heated to reflux for a further 4 hours (86-87° C.). The mixture wasthen cooled to <= 50° C. and filtered to remove the inorganics. Theinorganics were washed with a further 60 ml of methyl ethyl ketone whichwas then combined with the organic solution. The filter paper waspressed to maximise solvent and therefore product recovery. The organicswere then washed with 2×50 ml 10% potassium carbonate solution, followedby 3×50 ml water (ensuring the washings were neutral pH). The organicswere then heated on a rotary evaporator to remove the organic solventand any residual water (heating to 82° C. was required to drive off allof the solvent/water).

Product yield 36.32 g of a clear, slightly yellow liquid.

The product was analysed by IR.

IR: 1757-1739 cm⁻¹ C═O due to ester, 1082 cm⁻¹ and 1194 cm⁻¹ due toalkyl-aryl ether. No OH peak present

EXAMPLE 28

10 g of the sample from Example 27 (0.007 moles), 2-ITX sulphoxide, 7.6g (0.028 moles) and acetic anhydride (24 g) were mixed in a 250 ml3-necked round bottomed flask equipped with a stirrer, thermometer anddropping funnel.

Acetic anhydride (19 g) was added to a beaker and cooled to 10° C.Concentrated sulphuric acid (6.8 g) was added slowly controlling thetemperature below 20° C. The resulting mixture was charged to thedropping runnel and added to the mixture in the flask. The addition tookapproximately 15 minutes and produced a black solution. The solution wasstirred at room temperature for 20 minutes and then quenched slowly intoa mixture of potassium hexafluorophosphate (6 g), water (39 g) andacetonitrile (7 g), controlling the quenching temperature to 10-20° C. Asolid started to form during the quenching process but then started toform a paste. The paste was isolated by decanting off the excesssolvent. Product yield was not determined.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 29

Ethoxylated trimethylolpropane (7EO/3OH) 22.20 g (0.05 moles),bromoacetic acid 22.92 g (0.165 moles), p-toluenesulphonic acid 0.375 g,butylated hydroxytoluene-0.075 g and toluene 50 ml were mixed in a twonecked round-bottomed flask (flask 1) equipped with a temperature probe,condenser and Dean and Stark apparatus. The mixture was heated to refluxfor 5 hours and then cooled to room temperature and left overnight. In asecond flask (flask 2) equipped with a stirrer, condenser andtemperature probe 2-hydroxybiphenyl 25.5 g (0.15 moles), potassiumcarbonate 25.91 g (0.1875 moles) and methyl ethyl ketone 100 ml weremixed and heated to reflux for 3 hours and then cooled to roomtemperature and left overnight.

The contents of flask 1 were then added to flask 2. This mixture was menheated to reflux for a further 4 hours (86-87° C.). The mixture was thencooled to <−50° C. and filtered to remove the inorganics. The inorganicswere washed with a further 60 ml of methyl ethyl ketone which was thencombined with the organic solution. The filter paper was pressed tomaximise solvent and therefore product recovery. The organics were thenwashed with 2×50 ml 10% potassium carbonate solution, followed by 3×50ml water (ensuring the washings were neutral pH). The organics were thenheated on a rotary evaporator to remove the organic solvent and anyresidual water (heating to 82° C. was required to drive off all of thesolvent/water).

Product yield 40.88 g of a clear, slightly yellow liquid.

The product was analysed by IR.

IR: 1757-1737 cm⁻¹ C═O due to ester, 1080 cm⁻¹ and 1194 cm⁻¹ due toalkyl-aryl ether. No OH peak present.

EXAMPLE 30

10 g of the sample from Example 29 (0.00928 moles), 2-ITX sulphoxide,7.6 g (0.028 moles) and acetic anhydride (20 g) were mixed in a 250 ml3-necked round bottomed flask equipped with a stirrer, thermometer anddropping funnel.

Acetic anhydride (23 g) was added to a beaker and cooled to 10° C.Concentrated sulphuric acid (6.8 g) was added slowly controlling thetemperature below 20° C. The resulting mixture was charged to thedropping funnel and added to the mixture in the flask. The addition tookapproximately 15 minutes and produced a black solution. The solution wasstirred at room temperature for 20 minutes and then quenched slowly intoa mixture of potassium hexafluorophosphate (6 g), water (39 g) andacetonitrile (7 g), controlling the quenching temperature to 10-20° C. Asolid started to form during the quenching process but then started toform a paste. The paste was isolated by decanting off the excesssolvent. The product yield was not determined.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 31

Ethoxylated trimethylolpropane (3EO/3OH) 11.30 g (0.05 moles),bromoacetic acid 22.92 g (0.165 moles), p-toluenesulphonic acid 0.375 g,butylated hydroxytoluene 0.075 g and toluene 50 ml were mixed in a twonecked round-bottomed flask (flask 1) equipped with a temperature probe,condenser and Dean and Stark apparatus. The mixture was heated to refluxfor 5 hours and then cooled to room temperature and left overnight. In asecond flask (flask 2) equipped with a stirrer, condenser andtemperature probe 2-hydroxybiphenyl 25.5 g (0.15 moles), potassiumcarbonate 25.91 g (0.1875 moles) and methyl ethyl ketone 100 ml weremixed and heated to reflux for 3 hours and then cooled to roomtemperature and left overnight.

The contents of flask 1 were then added to flask 2. This mixture wasthen heated to reflux for a further 4 hours (86-87° C.). The mixture wasthen cooled to <= 50° C. and filtered to remove the inorganics. Theinorganics were washed with a further 60 ml of methyl ethyl ketone whichwas then combined with the organic solution. The filter paper waspressed to maximise solvent and therefore product recovery. The organicswere then washed with 2×50 ml 10% potassium carbonate solution, followedby 3×50 ml water (ensuring the washings were neutral pH). The organicswere then heated on a rotary evaporator to remove the organic solventand any residual water (heating to 82° C. was required to drive off allof the solvent/water).

Product yield 32.11 g of a clear, slightly yellow liquid.

The product was analysed by IR.

IR: 1757-1738 cm⁻¹ C═O due to ester, 1076 cm⁻¹ and 1194 cm⁻¹ due toalkyl-aryl ether. No OH peak present.

EXAMPLE 32

10 g of the sample from Example 31 (0.01164 moles), 2-ITX sulphoxide,9.4 g (0.0349 moles) and acetic anhydride (20 g) were mixed in a 250 ml3-necked round bottomed flask equipped with a stirrer, thermometer anddropping funnel.

Acetic anhydride (33 g) was added to a beaker and cooled to 10° C.Concentrated sulphuric acid (8.4 g) was added slowly controlling thetemperature below 20° C. The resulting mixture was charged to thedropping funnel and added to the mixture in the flask. The addition tookapproximately 15 minutes and produced a black solution. The solution wasstirred at room temperature for 20 minutes and men quenched slowly intoa mixture of potassium hexafluorophosphate (7.4 g), water (47 g) andacetonitrile (8.6 g), controlling the quenching temperature to 10-20° C.An oil formed which was isolated by decanting off the excess solventmixture. The product yield was not determined.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thioxanthone system was attached norcould the position of attachment on mat ring be determined.

EXAMPLE 33 Preparation of Thianthrene Sulphoxide

Thianthrene (5.0 g, 0.023 mol) was added to acetic acid (40 ml), stirredand heated to 110° C.-120° C. until completely dissolved. An excess ofperacetic acid (4.4 g, 0.058 mol) was then added dropwise and thereaction mixture continuously stirred at this temperature for fourhours. The reaction was followed using thin layer chromatography (TLC)using hexane:diethyl ether (80:20 by volume) as an indication ofthianthrene consumption because thianthrene and the sulphoxide have verydistinct and separate spots/rf values. After cooling, the reactionmixture was poured into water (80 ml), the resulting white precipitatefiltered off, washed with water and dried in a vacuum oven at 50° C. for4 hours.

Product yield 4.8 g (90%) of white crystals.

The product was analysed by IR, LCMS and HPLC

IR: 1078 cm⁻¹ and 1029 cm⁻¹ S═O due to sulphoxide.

MS: M/Z 233 (Mw of cation).

HPLC: one very strong peak due to product, with a change in retentiontime and a shift in the characteristic chromophore compared to thestarting material.

EXAMPLE 34

In a two-necked round bottomed flask (flask 1) equipped with a stirrer,condenser and temperature probe were added 5.36 g (0.0525382 moles)acetic anhydride. The temperature was reduced to ˜10° C. and 4.675 g(0.046455 moles) concentrated sulphuric acid was added dropwise,ensuring the temperature did not exceed 20° C.

In a second flask (flask 2) the following were mixed:—3.463 gthianthrene sulphoxide (0.0149252 moles, from Example 33),di(biphenyl-2-oxy)polytetrahydrofuran (5.0 g, 0.0074626 moles, fromExample 11), acetic anhydride (6.85 g). The flask was equipped with astirrer, thermometer and a condenser. The temperature of the mixture wasreduced to <10° C. using a water/ice bath. The contents from flask 1were then added to the contents of flask 2, ensuring the temperature wasmaintained <20° C. throughout. 2 g of acetic anhydride were used to washout flask 1 to ensure all of the mixture was added to flask 2. Themixture was then stirred for 30 minutes. The contents of the flask werethen added to 23.8 g methanol/20.2 g water/3.23 g potassiumhexafluorophosphate. (2 ml of methanol were used to ensure all of thecontents from the flask were washed into methanol/water/KPF6 saltmixture). The mixture was stirred for 30 minutes at approx. 40° C. Thetemperature was then reduced to approximately 10° C. and the mixturestirred for a further 30 minutes. The soluble materials were thendecanted off and the pasty material was washed/decanted with a further3×methanol/water (25.8 g/20.2 g). The resulting pasty solid was thendried in a vacuum oven at 40° C. for >4 hours. The solid product wasthen ground up using a mortar and pestle.

Product yield 7.14 g (68.84%) of a slightly yellow/brown solid.

The product was analysed by IR.

IR: 839 cm⁻¹ (strong) due to P—F salt of product.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each thianthrene system was attached norcould the position of attachment on that ring be determined.

EXAMPLE 35

In a two-necked round bottomed flask (flask 1) equipped with a stirrer,condenser and temperature probe add 5.36 g (0.0525382 moles) aceticanhydride. The temperature was reduced to ˜10° C. and 4.675 g (0.046455moles) concentrated sulphuric acid was added dropwise, ensuring thetemperature did not exceed 20° C.

In a second flask (flask 2) the following were mixed:—2.985 gdibenzothiophene sulphoxide (0.0149252 moles, from example 2),di(biphenyl-2-oxy)polytetrahydrofuran (5.0 g, 0.0074626 moles, fromExample 11), acetic anhydride (6.85 g). The flask was equipped with astirrer, thermometer and a condenser. The temperature of the mixture wasreduced to <10° C. using a water/ice bath. The contents from flask 1were then added to the contents of the second flask ensuring thetemperature was maintained <20° C. throughout. 2 g of acetic anhydridewere used to wash out flask 1 to ensure all of the mixture was added toflask 2. The mixture was then stirred for 30 minutes. The contents ofthe flask were then added to 23.8 g methanol/20.2 g water/3.23 gpotassium hexafluorophosphate. (2 ml of methanol were used to ensure allof the contents from the flask were washed into methanol/water/KPF6 saltmixture). The mixture was stirred for 30 minutes at approx. 40° C. Thetemperature was then reduced to approximately. 10° C. and the mixturestirred for a further 30 minutes. The soluble materials were thendecanted off and the pasty material was washed/decanted with a further3×methanol/water (25.8 g/20.2 g). The resulting pasty solid was thendried in a vacuum oven at 40° C. for >4 hours. The solid product wasthen ground up using a mortar and pestle.

Product yield 4.57 g (46.2%) of a brown solid.

The product was analysed by IR.

IR: 841 cm⁻¹ (strong) due to P—F salt of product.

It could not be determined by analysis to which of the benzene rings ofthe associated biphenyl system each dibenzothiophene system was attachednor could the position of attachment on that ring be determined.

EXAMPLE 36 Varnish Formulations

The following varnish formulations were used in the evaluationexperiments with all photoinitiators used at 4% active photoinitiator inthe formulation.

Description Standard Standard Experimental Material Code Varnish 1Varnish 2 Varnish Uvacure 1500 91.8 94.5 95.8 Tegorad 2100 0.2 0.2 0.2Uvacure 1592 8.0 — — Irgacure 250 — 5.3 — Experimental — — 4.0Photoinitiator Total 100.0 100.0 100.0

Uvacure 1500 is a cycloaliphatic epoxide monomer from UCB

Tegorad 2100 is a wetting aid from TEGO

Uvacure 1592 is a standard triarylsulphonium salt photoinitiator fromUCB (supplied as a 50% solution in propylene carbonate.)

Irgacure 250 is a standard diaryliodonium salt photoinitiator from CIBA(supplied as a 75% solution in propylene carbonate.)

The experimental photoinitiators used were those produced in Examples 4,5, 7, 9, 12, 14, 16, 18, 20, 26, 34 and 35.

Summary of Caring Experiments.

The varnishes were printed onto Leneta opacity charts using a No. 0K-bar and draw down pad. The prints were passed at 80 m/min through aPrimarc “Maxicure” UV curing rig using a single 300 W/inch mediumpressure mercury arc lamp operating on its half power setting. Thenumber of passes to achieve full cure was noted, along with the printcolour and odour.

All the experimental photoinitiators had acceptable cure performanceagainst the 2 commercial standard photoinitiators, with those containingthe initiators of Examples 4, 12 and 26 having cure at least as fast asthe best standard Uvacure 1592. All the experimental photoinitiatorswere soluble in fee test formulation and gave no odour on cure. Theslight yellowing observed with the experimental photoinitiators can beaddressed by formulation techniques known to those skilled in the art.The yellowing would not be an issue in pigmented inks containing theexperimental photoinitiators. The results are shown in the followingTable.

Curing Results Summary Number of passes to Initiator cure ExperimentalColour of Code Initiator Description Soluble varnish formulation Odourfilm Uvacure standard triarylsulphonium salt No 1 Strong Colourless 1592photoinitiator Irgacure standard diaryliodonium salt Yes 3 VeryColourless 250 photoinitiator strong Example PolyTHF250 Di(phenoxy Yes 1No Slightly 4 acetic)ester/2x2-ITX Yellow Example PolyTHF250 Di(phenoxyYes 4 No Slightly 5 acetic)ester/2xDBTP Yellow Example PolyTHF250Di(phenoxy Yes 2 No Slightly 7 propionic)ester/2x2-ITX yellow ExamplePolyTHF250 Di(phenoxy Yes 4 No Slightly 9 undecanoic)ester/2x2-ITXyellow Example PolyTHF250 Di(biphenyl-2-oxy Yes 1 No Slightly 12acetic)ester/2x2-ITX yellow Example Ethoxylated Pentaerythritol Yes 2 NoSlightly 14 (10EO/4OH) Teta(phenoxy yellow propionic)ester/4x2-ITXExample Ethoxylated Pentaerythritol Yes 2 No Slightly 16 (10EO/4OH)Tetra(phenoxy yellow acetic)ester/4x2-ITX Example Butoxylated TMPTri(phenoxy Yes 2 No Slightly 18 acetic)ester/3x2-ITX yellow ExamplePropoxylated Pentaerythritol Yes 2 No Slightly 20 (17PO/8OH)Tetra(phenoxy yellow acetic)ester/4x2-ITX Example EthoxylatedPentaerythritol Yes 1 No Slightly 26 (3EO/4OH) Tetra(biphenyl-2- yellowoxy acetic)ester/4x2-ITX Example PolyTHF250 Di(biphenyl-2-oxy Yes 2 NoColourless 34 acetic)ester/2xthianthrene Example PolyTHF250Di(biphenyl-2-oxy Yes 2 No Slightly 35 acetic)ester/ yellow2xdibenzothiophene

EXAMPLE 37 Magenta Ink Formulations

The following magenta ink formulations were used in the evaluationexperiments.

Description Material Code Standard Ink Experimental Ink Pigmentconcentrate 56.8 56.8 Uvacure 1500 34.7 34.7 Tegorad 2100 0.5 0.5Propylene carbonate 4.0 4.0 Standard Photoinitiator 4.0 — ExperimentalPhotoinitiator — 4.0

The standard photoinitiators used were Uvacure 1592 (triarylsulphoniumsalt photoinitiator from UCB, supplied as a 50% solution in propylenecarbonate) and Irgacure 250<diaryliodonium salt photoinitiator from CIBASpecialty Chemicals, supplied as a 75% solution in propylene carbonate).

Uvacure 1500 is a cycloaliphatic epoxide monomer from UCB

Tegorad 2100 is a wetting aid from TEGO

Summary of Curing Experiments.

The inks were printed onto a white OPP substrate (Propafilm RB30 ex UCB)using an “Easiproof” hand held flexo proofer with anilox tool 41. Theprints were passed through a Primarc Maxicure UV curing rig fitted witha 300 Watts/inch medium pressure mercury arc lamp at several differentline speeds and lamp power settings. The number of passes to achievecomplete cure was determined using the “thumb-twist” test.

Lamp at 100% Lamp at 50% power Power No. passes No. passes No. passes tocure to cure to cure Photoinitiator at 80 m/min at 100 m/min at 120m/min Uvacure 1592 1 2 2 Irgacure 250 — 4 2 Example 12 2-3 3 2

These results demonstrate that the novel photoinitiators of thisinvention have similar cure performance in inks to standard commercialcationic photoinitiators.

EXAMPLE 38 GC-MS Headspace Analysis from Varnishes

The following varnish formulations were used in the evaluationexperiments.

Description Sulphonium salt Iodonium salt Material Code formulationsformulation Uvacure 1500 75 77.5 TMPO 20.9 18.9 Tegorad 2100 0.1 0.1Propylene carbonate 2 — Photoinitiator 2 1.5 Esacure KIP 150 — 2

The standard photoinitiators used were Uvacure 1592 (triarylsulphoniumsalt photoinitiator from UCB, supplied as a 50% solution in propylenecarbonate) and IGM 440 (diaryliodonium salt photoinitiator from IGM.

Uvacure 1500 is a cycloaliphatic epoxide monomer from UCB

Tegorad 2100 is a wetting aid from TEGO

TMPO is a monofunctional oxetane alcohol diluent from Perstorp.

Esacure KIP 150 is a hydroxyalkylphenone photoinitiator from Lamberti.

The varnishes were printed onto aluminium foil using a No. 0 K-bar anddraw down pad. The prints were passed twice through a Primarc MaxicureUV curing rig fitted with a 300 Watts/inch medium pressure mercury arclamp at 80 m/min. Under these conditions the samples were over-cured,which was desirable in order to maximise the amount of by-productformation. 200 cm2 of each sample was placed in a sealed tube andsubjected to a standard headspace analysis procedure where they areheated to 200° C. for 10 minutes and then the headspace volumetransferred to a gas chromatograph fitted with a mass spectrometerdetector via a heated transfer line.

The compounds detected in these analyses are shown below. No attempt wasmade to quantify individual materials. Note that there were also severalpeaks common to all samples that derive from the Uvacure 1500.

Photoinitiator Materials detected in Head-space procedure derived fromphotoinitiator Uvacure 1592 Diphenyl sulphide Several small unidentifiedpeaks * IGM 440 Toluene Iodobenzene Several unidentified peaks Example 42-isopropyl thioxanthone unidentified phenoxy terminated material *Benzene would also be expected from this analysis but was not seen dueto the solvent delay used in this standard GC method.

These results demonstrate that for Example 4, the photoinitiatorby-products detected are the commonly used free radical photoinitiatorITX, and an unidentified phenoxy terminated material. In the case ofthis phenoxy by-product, its occurrence can be limited further throughthe use of higher functionality and/or higher molecular weight polyolstating materials. These results contrast with the undesirable materialsreleased from the 2 standard photoinitiators.

GC-MS Headspace Analysis from Inks

The following ink formulations were used in the evaluation experiments.

GC-MS Headspace Analysis from Inks

The following ink formulations were used in the evaluation experiments,

Description Sulphonium salt Iodonium salt Material Code formulationsformulation Pigment concentrate 54 54 Uvacure 1500 4.2 4.2 TMPO 33.332.3 Tegorad 2100 0.5 0.5 Propylene carbonate 4 4 Photoinitiator 4 3Irgacure 184 — 2

The standard photoinitiators used were Uvacure 1592 (triarylsulphoniumsalt photoinitiator from UCB, supplied as a 50% solution in propylenecarbonate) and IGM 440 (diaryliodonium salt photoinitiator from IGM.

Irgacure 184 is a hydroxyalkylphenone photoinitiator from CIBA. Allother raw materials are as disclosed above.

Inks were printed onto aluminium foil using an “Easi-proof” hand aniloxflexo proofer and cured on a Primarc Maxicure UV rig at 100 m/min with asingle 300 W/inch medium pressure mercury arc lamp operating at fullpower.

250 cm² of each sample was placed in a sealed tube and subjected to astandard headspace analysis procedure where they are heated to 200° C.for 10 minutes and then the headspace volume transferred to a gaschromatograph fitted with a mass spectrometer detector via a heatedtransfer line.

The compounds detected in these analyses are shown below. No attempt wasmade to quantify individual materials. Note that there were also severalpeaks common to all samples that derive from the Uvacure 1500.

Photoinitiator Materials detected in Head-space procedure derived fromphotoinitiator Uvacure 1592 Diphenyl sulphide Several small unidentifiedpeaks * IGM 440 Toluene Iodobenzene Several unidentified peaks Example12 2-isopropyl thioxanthone * Benzene would also be expected from thisanalysis but was not seen due to the solvent delay used in this standardGC method.

These results demonstrate that for Example 12, the only photoinitiatorby-product detected was the commonly used free radical photoinitiatorITX. This result contrasts with the undesirable materials released fromthe 2 standard photoinitiators.

1. Compounds of formula (I):

where: R¹ represents a direct bond; R³, R⁴, R⁵ and R⁶ are independentlyselected from hydrogen atoms and substituents α, defined below; R⁸, R⁹,R¹⁰ and R¹¹ are independently selected from hydrogen atoms, hydroxygroups, C₁-C₄ alkyl groups, and phenyl groups which are unsubstituted orsubstituted by at least one substituent selected from the groupconsisting of C₁-C₄ alkyl groups and C₁-C₄ alkoxy groups; or R⁹ and R¹¹are joined to form a fused ring system with the benzene rings to whichthey are attached; R⁷ represents a direct bond, an oxygen atom or a—CH₂— group; p is 0 or 1; said substituents α are: a C₁-C₂₀ alkyl group,a C₁-C₂₀ alkoxy group, a C₂-C₂₀ alkenyl group, a halogen atom, a nitrileatom, a hydroxyl group, a C₆-C₁₀ aryl group, a C₇-C₁₃ aralkyl group, aC₆-C₁₀ aryloxy group, a C₇-C₁₃ aralkyloxy group, a C₈-C₁₂ arylalkenylgroup, a C₃-C₈ cycloalkyl group, a carboxy group, a C₂-C₇ carboxyalkoxygroup, a C₂-C₇ alkoxycarbonyl group, a C₇-C₁₃ aryloxycarbonyl group, aC₂-C₇ alkylcarbonyloxy group, a C₁-C₆ alkanesulphonyl group, a C₆-C₁₀arenesulphonyl group, a C₁-C₆ alkanoxyl group or a C₇-C₁₁ arylcarbonylgroup; n is a number from 1 to 12; R¹² represents a hydrogen atom, amethyl group or an ethyl group, and, when n is greater than 1, thegroups or atoms represented by R¹² may the same as or different fromeach other; A represents a group of formula —[O(CHR¹³CHR¹⁴)_(a)]_(y)—,—[O(CH₂)_(b)CO]_(y)—, or —[O(CH₂)_(b)CO]_((y-1))—[O(CHR¹³CHR¹⁴)_(a)]—,where: one of R¹³⁻ and R¹⁴ represents a hydrogen atom and the otherrepresents a hydrogen atom, a methyl group or an ethyl group; a is anumber from 1 to 2; b is a number from 4 to 5; Q is a residue of apolyhydroxy compound having from 2 to 6 hydroxy groups; x is a numbergreater than 1 but no greater than the number of available hydroxylgroups in Q; y is a number from 1 to 10; and X⁻ represents an anion; andesters thereof.
 2. Compounds according to claim 1, in which x is anumber greater than 1 but no greater than 2, and y is a number from 1 to10; or in which x is a number greater than 2, and y is a number from 3to
 10. 3. Compounds according to claim 1, in which n is a number from 1to
 6. 4. Compounds according to claim 1, in which n is
 1. 5. Compoundsaccording to claim 1, in which R¹² represents a hydrogen atom. 6.Compounds according to claim 1, in which n is a number from 2 to 6 andone group R¹² represents a hydrogen atom, or a methyl or ethyl group andthe other or others R¹² represent hydrogen atoms.
 7. Compounds accordingto claim 1, in which y is a number from 3 to
 10. 8. Compounds accordingto claim 1, in which A represents a group of formula—[O(CHR¹³CHR¹⁴)_(a)]_(y)—, where a is an integer from 1 to 2, and y is anumber from 3 to
 10. 9. Compounds according to claim 1, in which Arepresents a group of formula —[OCH₂CH₂]_(y)—, —[OCH₂CH₂CH₂CH₂]_(y)— or—[OCH(CH₃)CH₂]_(y)—, where y is a number from 3 to
 10. 10. Compoundsaccording to claim 1, in which A represents a group of formula—[O(CH₂)_(b)CO]_(y)—, where b is a number from 4 to 5 and y is a numberfrom 3 to
 10. 11. Compounds according to claim 1, in which A representsa group of formula —[O(CH₂)_(b)CO]_((y-1))—[O(CHR¹³CHR¹⁴)_(a)]—, where ais a number from 1 to 2, b is a number from 4 to 5 and y is a numberfrom 3 to
 10. 12. Compounds according to claim 1, in which x is 2 and yis a number from 1 to
 10. 13. Compounds according to claim 1, in which yis a number from 3 to
 6. 14. Compounds according to claim 1, in whichthe residue Q-(A-)_(x) has a molecular weight no greater than
 2000. 15.Compounds according to claim 14, in which the residue Q-(A-)_(x) has amolecular weight no greater than
 1200. 16. Compounds according to claim15, in which the residue Q-(A-)_(x) has a molecular weight no greaterthan
 1000. 17. Compounds according to claim 16, in which the residueQ-(A-)_(x) has a molecular weight no greater than
 800. 18. Compoundsaccording to claim 1, in which Q is a residue of ethylene glycol,propylene glycol, butylene glycol, glycerol, trimethylolpropane,di-trimethylolpropane, pentaerythritol or di-pentaerythritol. 19.Compounds according to claim 1, in which R³, R⁴, R⁵ and R⁶ areindependently selected from hydrogen atoms, C₁-C₁₀ alkyl groups, C₁-C₁₀alkoxy groups, halogen atoms, and C₃-C₈ cycloalkyl groups.
 20. Compoundsaccording to claim 1, in which three or four of R³, R⁴, R⁵ and R⁶represents hydrogen atoms.
 21. Compounds according to claim 19, in whichone or more R³, R⁴, R⁵ and R⁶ represents an ethyl or isopropyl group.22. Compounds according to claim 1, in which two, three or four of R⁸,R⁹, R¹⁰ and R¹¹ represents hydrogen atoms.
 23. Compounds according toclaim 1, in which all of R⁸, R⁹, R¹⁰ and R¹¹ represent hydrogen atoms.24. Compounds according to claim 1, in which R¹ represents a group >C═O.25. (canceled)
 26. Compounds according to claim 1, in which that part ofthe compound of formula (I) having the formula (IV):

(in which R¹, R³, R⁴, R⁵ and R⁶ are as defined in claim 1) is a residueof substituted or unsubstituted, dibenzothiophene.
 27. (canceled) 28.(canceled)
 29. (canceled)
 30. (canceled)
 31. (canceled)
 32. Compoundsaccording to claim 1, in which: R³, R⁴, R⁵ and R⁶ are individually thesame or different and each represents a hydrogen atom or an alkyl grouphaving 1 to 4 atoms; R⁷ is a direct bond; R⁸, R⁹, R¹⁰ and R¹¹ representhydrogen atoms; and A represents a group of formula—[OCH₂CH₂CH₂CH₂]_(y)—; and Q represents a residue of butylene glycol.33. Compounds according to claim 1, in which R³, R⁴, R⁵ and R⁶ areindividually the same or different and each represents a hydrogen atomor an alkyl group having from 1 to 4 carbon atoms; R⁷ represents adirect bond; R⁸, R⁹, and R¹¹ represent hydrogen atoms; R¹⁰ represents aphenyl group; p is 0; A represents a group of formula—[OCH₂CH₂CH₂CH₂]_(Y)—; and Q represents a residue of butylene glycol.34. Compounds according to claim 1, in which X⁻ represents PF₆ ⁻, SbF₆⁻, AsF₆ ⁻, BF₄ ⁻, B(C₆F₅)₄ ⁻, R^(a)B(Ph)₃ ⁻ (where R^(a) represents aC₁-C₆ alkyl group and Ph represents a phenyl group), R^(b)SO₃ ⁻ (whereR^(b) represents a C₁-C₆ alkyl or haloalkyl group or an aryl group),ClO₄ ⁻, or ArSO₃ ⁻ (where Ar represents an aryl group) group. 35.Compounds according to claim 33, in which X⁻ represents PF₆ ⁻, SbF₆ ⁻,AsF₆ ⁻, CF₃SO₃ ⁻ or BF₄ ⁻ group.
 36. Compounds according to claim 34, inwhich X⁻ represents a PF₆ ⁻ group.
 37. Compounds according to claim 1,having the formula (Ia):

in which R¹, R³, R⁴, R⁵, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², p, x, n, A, Y and X⁻are as defined in claim
 1. 38. An energy-curable composition comprising(a) a polymerizable monomer, prepolymer or oligomer; and (b) aphotoinitiator which is a compound of formula (I), as claimed inclaim
 1. 39. A process for preparing a cured polymeric composition byexposing a composition according to claim 38 to curing energy.
 40. Aprocess according to claim 39, in which the curing energy is ultravioletradiation.